This invention relates generally to the manufacture of balloon catheters having inflatable expander members or balloon members, and to the balloon catheters made thereby.
Balloon catheters are well known and used regularly for coronary angioplasty procedures and other similar procedures. In an angioplasty procedure, an occluded blood vessel, i.e., one containing a stenosis, is treated by the inflation of a balloon member which expands the vessel lumen thus pressing the stenotic lesion back against the vessel wall. Such stenosis are often the result of atheromatous plaque adhering to a blood vessel wall and restricting blood flow therethrough which is compressed against the vessel wall by the balloon balloon member which is positioned in the vessel at the plaque location and then expanded. This dilates the vessel lumen to permit increased blood flow.
Typically, the expander member or balloon is carried on the distal end of a dilatation catheter assembly which is routed through a guide catheter that has been previously advanced through the vascular system to a location that is proximal to, for example, the coronary artery having the stenotic lesion. Following placement of the balloon member across the lesion as desired, fluid is introduced into the proximal end of the catheter to inflate the balloon member to a relatively high pressure, thereby restoring patency to the vessel.
A typical balloon catheter includes two lengthwise lumens or channels, one for inflation of an inflatable balloon tacked to the distal catheter end and the other for insertion of a guidewire extending through the catheter to aid in positioning the catheter during use.
Prior to its inflation while treating a stenotic lesion, the balloon or expander member is tightly wrapped or folded so as to exhibit a low profile at the distal end of the angioplasty catheter. This facilitates its ability to be routed through the lumen of a guide catheter and into a coronary artery for placement adjacent the lesion to be treated. Once the balloon has been inflated by injecting an inflation fluid through the inflation lumen and out the inflation port, the inflation fluid is evacuated. However, commonly employed balloon materials do not evacuate as desired, “winging” or “pancaking” upon evacuation of the inflation fluid may occur as described in U.S. Pat. No. 5,681,522. That is to say, evacuation of the inflation fluid does not result in the balloon member again tightly re-wrapping and conforming to the periphery of the catheter body. This makes it difficult to withdraw the distal end portion of the catheter back into the lumen of the guide catheter with which it is used or to perform additional manipulation of the balloon catheter within the vasculature. Thus, such balloons are said to lack sufficient rewrap such that they can be removed easily after deflation.
U.S. Pat. No. 5,853,389, there is disclosed a large balloon for a balloon catheter having a tubular central section and, when inflated, frustoconical transition sections on either end of the central section connecting with tubular end sections of less diameter than the central section. The transition sections have spiral ridges of material extending from each end section toward the central section, and in which, in deflated condition, the central second and the transition sections are folded in pleats as urged by the spiral ridges.